Then it grosses you out, and then it doesn’t?

Second-year Psychology students participating in the University Honours College or in the Departmental Excellence Program complete a Research Seminar in which they learn to communicate science to various audiences, including the general public. For one assignment, the students write a popular science paper. This year a selection of these papers is published on Mindwise. Today’s piece is by Bregje Faasse.

The famous Paul Ekman observed the emotion of disgust in many different cultures (Ekman & Friesen, 1971). However, it is still unclear how this particular emotion emerges in humans. Nowadays, there is a widely accepted theory that disgust evolved to help us avoid contaminants in the environment. In light of this theory it is not surprising that faeces and rotten food readily elicit a disgust response. This makes sense, because this way disgust prevents us from eating anything contagious and harmful, anything that could poison or even kill us.

Nonetheless, disgust can also play a big part in the maintenance of phobias, post-traumatic stress disorder, and eating disorders. In these cases the disgust response is considered maladaptive rather than adaptive. Clinical psychology researchers at the University of Groningen are currently investigating the mechanisms behind disgust learning and if this learned disgust response is resistant against extinction.

“Clinical psychology researchers at the University of Groningen are currently investigating the mechanisms behind disgust learning”

For example, together with Necj Dolensek, Anja Ernst, and Dominika Lisy, I was involved in an experiment by Charmaine Borg and Peter de Jong that was based on the general idea that a disgust response can be learned via classical conditioning (Borg, Bosman, Engelhard, Olatunji, & de Jong, 2014). As earlier research found a difference between men and woman regarding disgust propensity and sensitivity, only women could participate. We researched the learned disgust response over time, because previous research suggested that it may be resistant to extinction. In the first (baseline) phase of the study, participants were exposed to pictures of two food items: pea soup and a sausage roll. In the second phase, participants learned to experience disgust towards one of these food items. We managed to teach participants this by showing a video of a girl vomiting after they had seen the picture of the pea soup (or the sausage roll).

The third phase of the study involved exposure to the food item that was now associated with disgust, let’s say pea soup. In this phase some participants were asked to perform a task in which they were asked to eat a bit of the pea soup, thus allowing them to experience that in fact nothing was wrong with the soup. Other participants saw a video of a woman eating the pea soup without any sign of disgust as a more indirect way to signal that the soup was OK. A third group saw a video of a woman being exposed to the pea soup but not eating it. This condition served as a control for the influence of being merely exposed to the soup. As an additional control condition, a final subgroup of participants did nothing of the above. In all groups, we subsequently presented again a series of pictures of the pea soup (and the sausage roll) and assessed the participants’ willingness to eat the soup (and the roll), how disgusting they found these food items, and how pleasant they found these foods.

In the fourth phase of the study we brought the pea soup and the control item (the roll) into the room where the participant was sitting. She was asked to take a bite from both items. This made it possible to measure how her facial muscles moved in response to the idea of eating the pea soup compared to the control item. In other words did she specifically wrinkle her nose when presented with the pea soup, as a disgusted person would. Finally, to answer our question whether learned disgust is resistant over time, we sent participants two questionnaires after they had gone home. The first questionnaire was sent after 24 hours, the second one after 7 days.

We expect to find a difference in liking between the food item that we taught participants to find disgusting and the neutral food item. We also expect that the different kinds of exposure (in the four different groups as described above) would have different effects on the extinction of disgust over time. Further, we are curious to find out if there will be a difference between self-reported disgust levels and the facial muscle data.

This research may have important implications for clinical treatment in the future, for example to treat certain phobias. Hopefully, we will know a little more about this complex emotion, disgust.

Ekman, P., Friesen, W.V. (1971). Constants across cultures in the face and emotion. Journal of Personality and Social Psychology, 17 (2), 124-129.

Author: Bregje Faasse

Bio: This coming year Bregje Anna Maartje Faasse will be a third-year psychology student. Besides her regular studies she is also enrolled in the Honours College, where she attends deepening and broadening courses. She finds these courses a real addition, especially the broadening courses are the perfect opportunity to expand her knowledge in different fields. For example, Bregje is currently taking a course called Urbanisation Question regarding social geography and secularization in New York City. This provides a nice change to the regular psychology courses.

Currently Bregje is particularly interested in cognitive psychology and neuropsychology as well as medical psychology. In the upcoming year she is planning to complete the Neuroscience minor. Bregje is still deciding what to do after completing the Bachelor program. A future research career is a serious option, however, a clinical career also remains one of the options. Combing both would probably be the perfect match.

Dr. aan het Rot completed her doctoral degree at McGill University (Montreal, Canada) and was a postdoctoral fellow at the Mount Sinai School of Medicine (New York, USA). She works at the University of Groningen since 2009 and is currently affiliated with the Heymans Institute for Psychological Research and with the Groningen School of Behavioral and Cognitive Neuroscience (BCN). Her research interests concern the role of social and biological factors in the development and maintenance of psychological problems. More specifically, Dr. aan het Rot is interested in (1) the role of interpersonal factors in the development and maintenance of psychological disorders, and (2) the biological factors that underlie poor interpersonal functioning. Dr. aan het Rot teaches in the Dutch and English Bachelor and Master programs of Psychology. For more information, you can visit her website.